Thiamethoxam toxicity on the stingless bee Friesiomelitta varia: LC, survival time, and enzymatic biomarkers assessment.

Bees play a crucial role as pollinating insects in both natural and cultivated areas. However, the use of pesticides, such as thiamethoxam, has been identified as a contributing factor compromising bee health. The current risk assessment primarily relies on the model species Apis mellifera, raising concerns about the applicability of these assessments to other bee groups, including stingless bees.

Sublethal exposure to thiamethoxam and pyraclostrobin affects the midgut and Malpighian tubules of the stingless bee Frieseomelitta varia (Hymenoptera: Apidae: Meliponini).

The stingless bee Frieseomelitta varia Lepeletier 1836 (Hymenoptera: Apidae) is an essential pollinator in natural and agricultural ecosystems in the Neotropical region. However, these bees may be exposed to pesticides during foraging, which can affect both individuals and their colonies. One example comes from the use of pyraclostrobin (a fungicide) and thiamethoxam (an insecticide) for pest control in pepper crops, which F.

Effects of chronic exposure to sublethal doses of neonicotinoids in the social wasp Polybia paulista: Survival, mobility, and histopathology.

Several studies have investigated the consequences of exposure to neonicotinoids in honeybees. Given the lack of studies concerning the consequences of exposure of social wasps to neonicotinoids, as well as the ecological importance of these insects, the objective of this study was to test the hypothesis that chronic exposure to sublethal concentrations of thiamethoxam decreases survival and mobility by causing damage to the brain and midgut of the social wasp Polybia paulista. The wasps were exposed to different concentrations of thiamethoxam, in order to obtain the mean lethal concentration (LC), which was used as a reference for calculation of two sublethal concentrations (LC and LC) employed in subsequent experiments.

Neonicotinoid effects on tropical bees: Imidacloprid impairs innate appetitive responsiveness, learning and memory in the stingless bee Melipona quadrifasciata.

Together with other anthropogenic factors, pesticides play a major role in pollinator decline worldwide. Most studies on their influence on pollinators have focused on honey bees given the suitability of this insect for controlled behavioral testing and raising. Yet, studies on pesticide impact should also contemplate tropical species, which contribute a major part of biodiversity and which have remained so far neglected.

Lethal and Sublethal Dose of Thiamethoxam and Its Effects on the Behavior of a Non-target Social Wasp.

In the last few years, with the increase in agricultural productivity, there has also been an increase in the use of insecticides to combat insects considered pests. However, these chemical compounds end up affecting nontarget insects that also interact with the crops. Studies have shown that social bees are among the insects that are suffering most from the effects of these compounds, resulting in negative ecological and economic impacts, considering that these insects provide pollination services in ecosystems.

Surrogate species in pesticide risk assessments: Toxicological data of three stingless bees species.

Discussions about environmental risk reassessment of pesticides have grown in the last decades, especially in tropical and subtropical regions since the diversity of bee species in these places is quite different. Stingless bees are highly affected by pesticides, and toxicity information is necessary to include them in the regulatory process of countries that hosts a diversity of these species. Therefore, the present study aimed to evaluate the Median Lethal Concentration (LC), estimate the Median Lethal Dose (LD) and compared the sensitivity of three species of stingless bees exposed to the commercial formulation of the neonicotinoid thiamethoxam (TMX).

Fungivorous mites enhance the survivorship and development of stingless bees even when exposed to pesticides.

Stingless bees are the largest group of eusocial bees in the world. They play an essential role as crop pollinators and have been considered for inclusion in pesticide risk assessments (RAs). Beyond the mutualism involving stingless bee larvae and fungi, the fungivorous mite Proctotydaeus (Neotydeolus) alvearii proved to be interesting for studies of associations with stingless bees.

Transcriptomic analysis of Malpighian tubules from the stingless bee Melipona scutellaris reveals thiamethoxam-induced damages.

The concern about pesticide exposure to neotropical bees has been increasing in the last few years, and knowledge gaps have been identified. Although stingless bees, (e.g.

Optimization of in vitro culture of honeybee nervous tissue for pesticide risk assessment.

The most used pesticides have neurotoxic action on the neurotransmitter system of target and non-targeted insects, such as honeybees. However, honeybees have foremost importance worldwide, which has encouraged the development of tools to evaluate the action of specific pesticide molecules on their nervous system, providing accurate data on damage to their brain. In this sense, our study aimed to optimize in vitro honeybee nervous tissue culture to assess pesticide risks.

A systematic review of research conducted by pioneer groups in ecotoxicological studies with bees in Brazil: advances and perspectives.

Brazil presents the most threatened endemic or rare species among neotropical regions, with the Hymenoptera order, to which bees belong, classified as a high-risk category. In Brazil, the main cause of bee death is the indiscriminate use of pesticides. In this context, groups such as Bee Ecotoxicology and Conservation Laboratory (LECA in Portuguese) and Bees and Environmental Services (ASAs in Portuguese) have become a reference in studies evaluating the impacts of pesticides on bees since 1976.

Is the social wasp Polybia paulista a silent victim of neonicotinoid contamination?

Neonicotinoids are among the chemicals most widely used against insects considered agricultural pests, although they may also affect nontarget species, as has been reported for social bees. Social wasps are recognized as efficient predators of larvae of other insects, including pest species, so they may have contact with insecticides, at least indirectly. However, to date, there have been no studies investigating the consequences for social wasps of the use of neonicotinoids.

Removal of the pesticide thiamethoxam from sugarcane juice by magnetic nanomodified activated carbon.

The removal of the neonicotinoid and systemic pesticide thiamethoxam (TMX) from water and sugarcane juice by magnetic nanomodified activated carbon (AC-NP) is proposed. This adsorbent was synthesized and characterized by FTIR, XRD, and SEM, and TMX was quantified by high-performance liquid chromatography coupled to a diode array detector (HPLC-DAD). The AC-NP was efficiently synthesized using a co-precipitation method and the impregnation of magnetite (NP) in the activated carbon (AC) was assessed by the crystalline planes found in the AC-NP structure shown in the XRD diffractograms.

Is the Water Supply a Key Factor in Stingless Bees' Intoxication?

Water is an important resource for stingless bees, serving for both honey dilution and the composition of larval food inside nests, yet can be an important route of exposure to pesticides. Assuming bees can forage naturally on pesticide-contaminated or noncontaminated areas, we investigated whether water supply influences the choice between neonicotinoid-dosed or nondosed feeders and on mortality of the stingless bee, Melipona scutellaris (Latreille, Hymenoptera, Apidae). At the field concentration, there was no significant mortality; however, the bees were not able to distinguish the feeders.

A high quality method for hemolymph collection from honeybee larvae.

The drastic decline of bees is associated with several factors, including the immune system suppression due to the increased exposure to pesticides. A widely used method to evaluate these effects on these insects' immune systems is the counting of circulating hemocytes in the hemolymph. However, the extraction of hemolymph from larvae is quite difficult, and the collected material is frequently contaminated with other tissues and gastrointestinal fluids, which complicates counting.

What is the most suitable native bee species from the Neotropical region to be proposed as model-organism for toxicity tests during the larval phase?

Currently, Brazil has a full framework for pesticide risk assessment established for Apis mellifera, based on the North American approach. However, the use of Apis mellifera as model-organism as a surrogate for Brazilian native species of stingless bees has been questioned. Assessments on other stages of development than adult individual are essential.

Occurrence of virus, microsporidia, and pesticide residues in three species of stingless bees (Apidae: Meliponini) in the field.

Bees are important pollinators whose population has declined due to several factors, including infections by parasites and pathogens. Resource sharing may play a role in the dispersal dynamics of pathogens among bees. This study evaluated the occurrence of viruses (DWV, BQCV, ABPV, IAPV, KBV, and CBPV) and microsporidia (Nosema ceranae and Nosema apis) that infect Apis mellifera, as well as pesticide residues in the stingless bees Nannotrigona testaceicornis, Tetragonisca angustula, and Tetragona elongata sharing the same foraging area with A.

Standardization of in vitro nervous tissue culture for honeybee: A high specificity toxicological approach.

Bees are important pollinators that help to maintain the biodiversity of wild and cultivated plants. However, the increased and inappropriate use of agrochemicals has caused an imbalance in the populations of these insects visiting flowers for pollen and nectar collection. Therefore, new research methods for understanding the mechanisms of action of pesticides and their impacts on the brains of bees, such as neurotoxicity and cellular changes, in response to different active characteristics and dosages of insecticides are necessary.

Correction: In vitro larval rearing protocol for the stingless bee species Melipona scutellaris for toxicological studies.

[This corrects the article DOI: 10.1371/journal.pone.

In vitro larval rearing protocol for the stingless bee species Melipona scutellaris for toxicological studies.

Brazil has the highest biodiversity of native stingless bees in the world. However, Brazilian regulations are based on protocols standardized by the Organization for Economic Cooperation and Development (OECD), which uses Apis mellifera as a model organism. The safety of the use of an exotic species as a substitute for a native species is a problem that concerns members of the academy and the government agencies responsible for studies of this nature in the neotropical regions where there are occurrences of stingless bee species.

Pesticide Exposure Assessment Paradigm for Stingless Bees.

Although the importance of bees as the pollinators responsible for maintaining gene flow for many native and cultivated plants in ecosystems around the world is recognized, much of their biodiversity and behavior remains to be discovered. Stingless bees are considered key pollinators for several plant species in tropical and subtropical ecosystems and they also provide pollination services for economically important agricultural crops. Many countries are using the honey bee (Apis mellifera Linnaeus, 1758, Hymenoptera: Apidae) as a surrogate to evaluate the risk of pesticides to all species of bees.

Exposure to thiamethoxam during the larval phase affects synapsin levels in the brain of the honey bee.

Thiamethoxam (TMX) is a neurotoxic insecticide widely used for insect pest control. TMX and other neonicotinoids are reported to be potential causes of honey bee decline. Due to its systematic action, TMX may be recovered in pollen, bee bread, nectar, and honey, which make bees likely to be exposed to contaminated diet.

Changes in Synapsin Levels in the Millipede Gymnostreptus olivaceus Schubart, 1944 Exposed to Different Concentrations of Deltamethrin.

Millipedes are ecologically important soil organisms and may also be an economically threatening species in rural and urban areas when population outbreaks occur. In order to control infestations commercial formulations of deltamethrin have been commonly applied, even though there are few studies about the effects of such insecticide on millipedes. This paper describes the effects of this insecticide on millipedes showing neurotoxic effects assessed by synapsin labeling and confocal microscopy.

Sublethal doses of fipronil intensify synapsin immunostaining in Atta sexdens rubropilosa (Hymenoptera: Formicidae) brains.

Background: Although ants are common insects in agricultural ecosystems, few studies have considered how xenobiotics might induce physiological and morphological alterations in these insects. This study aimed to verify the neurotoxic action of sublethal doses of fipronil on the mushroom bodies of brains from the leaf-cutting ant Atta sexdens rubropilosa through immunocytochemistry analysis for the protein synapsin.

Results: The LD50 value was established as 1.

Toxicity of Imidacloprid to the Stingless Bee Scaptotrigona postica Latreille, 1807 (Hymenoptera: Apidae).

The stingless bee Scaptotrigona postica is an important pollinator of native and cultivated plants in Brazil. Among the factors affecting the survival of these insects is the indiscriminate use of insecticides, including the neonicotinoid imidacloprid. This work determined the toxicity of imidacloprid as the topical median lethal dose (LD50) and the oral median lethal concentration (LC50) as tools for assessing the effects of this insecticide.